Many individuals with autism spectrum disorder (ASD) have symptoms of sensory hypersensitivity. Several studies have shown high individual variations in temporal processing of tactile stimuli. We hypothesized that these individual differences are linked to differences in hyper-reactivity among individuals with ASD. Participants performed two tasks as to vibrotactile stimuli: One is a temporal order judgement task, and another is a detection task. We found that individuals with ASD with higher temporal resolution tended to have more severe hypersensitivity symptoms. In contrast, the tactile detection threshold/sensitivity were related to the severities of stereotyped behaviour and restricted interests, rather than to hypersensitivity. Our findings demonstrate that higher temporal resolution to sensory stimuli may contribute to sensory hypersensitivity in individuals with ASD.

Autism spectrum disorder (ASD) is a neurodevelopmental disorder characterized by deficits in social communication and interaction, and restricted interests and behavior patterns. These characteristics are considered as a continuous distribution in the general population. People with ASD show atypical temporal processing in multisensory integration. Regarding the flash–beep illusion, which refers to how a single flash can be illusorily perceived as multiple flashes when multiple auditory beeps are concurrently presented, some studies reported that people with ASD have a wider temporal binding window and greater integration than typically developed people; others found the opposite or inconsistent tendencies. Here, we investigated the relationships between the manner of the flash–beep illusion and the various dimensions of ASD traits by estimating the degree of typically developed participants’ ASD traits including five subscales using the Autism-Spectrum Quotient. We found that stronger ASD traits of communication and social skill were associated with a wider and narrower temporal binding window respectively. These results suggest that specific ASD traits are differently involved in the particular temporal binding processes of audiovisual integration.

Autism spectrum disorder (ASD) includes characteristics such as social and behavioral deficits that are considered common across the general population rather than unique to people with the diagnosis. People with ASD are reported to have sensory irregularities, including crossmodal perception. Crossmodal correspondences are phenomena in which arbitrary crossmodal inputs affect behavioral performance. Crossmodal correspondences are considered to be established through associative learning, but the learning cues are considered to differ across the types of correspondences. In order to investigate whether and how ASD traits affect crossmodal associative learning, this study examined the relationships between the magnitude of crossmodal correspondences and the degree of ASD traits among non-diagnosed adults. We found that, among three types of crossmodal correspondences (brightness–loudness, visual size–pitch, and visual location–pitch pairs), the brightness–loudness pair was related with total ASD traits and a subtrait (social skill). The magnitude of newly learned crossmodal associations (the visual apparent motion direction–pitch pair) also showed a relationship with an ASD subtrait (attention switching). These findings demonstrate that there are unique relationships between crossmodal associations and ASD traits, indicating that each ASD trait is differently involved in sensory associative learning.